Molding tool

Abstract

A molding tool for use in pressing operations for pressing powder material, in particular coffee powder, includes a concave, in particular dome-shaped, pressing surface. On the pressing surface there is an extensive non-stick texture for preventing powder material, in particular coffee powder, from adhering. The non-stick texture includes a multiplicity of local recess structures, wherein the recess structures each have a depth of 0.04 mm to 0.2 mm, in particular a depth of 0.08 mm to 0.14 mm. The non-stick texture prevents powder material from adhering during and after a pressing operation, even in the case of powder materials containing oil, e.g. coffee powder. It also prevents such adhering for different types of coffee and in pressing operations in which high pressures arise.

Claims

1. A molding tool for use in pressing operations for pressing powder material, comprising; a concave pressing surface, wherein an extensive non-stick texture is located on the pressing surface to prevent powder material from adhering, wherein the non-stick texture comprises a multiplicity of local recess structures and wherein the recess structures each have a depth of 0.04 mm to 0.2 mm.

2. The molding tool according to claim 1, wherein the local recess structures are laser engraved.

3. The molding tool according to claim 2, where the laser engraved recess structures are laser engraved at a laser incidence angle of at most 40.

4. The molding tool according to claim 2, wherein the recess structures are each laser engraved through a plurality of individual ablations, wherein an individual ablation in each case produces a local recess with a depth of 0.0002 mm to 0.0006 mm.

5. The molding tool according to claim 4, wherein the recess structures are each laser engraved through at least 10 and at most 50 individual ablations.

6. The molding tool according to claim 2, wherein the recess structures are laser engraved by a laser with a focus diameter of 0.005 mm to 0.2 mm.

7. The molding tool according to claim 2, wherein the recess structures are laser engraved by an ytterbium fiber laser.

8. The molding tool according to claim 7, wherein the non-stick texture comprises local raised structures, the raised structures being adjacent to the local recess structures, and the raised structures having a height of 0.01 mm to 0.14 mm.

9. The molding tool according to claim 1, wherein the local recess structures each have a maximum extensive expansion of 0.00002 mm.sup.2 to 0.03 mm.sup.2at half their depth.

10. The molding tool according to one of claim 1, wherein the local recesses are located within a multiplicity of macro-areas, each macro-area having an extensive expansion of 0.3 mm2 to 3.0 mm2 on the pressing surface, wherein the macro-areas are separated from one another by boundary areas having shallower depths than the depth of the local recess structures.

11. The molding tool according to claim 10, wherein the macro-areas of the non-stick texture have a hexagon shape and are arranged on the pressing surface in a hexagon honeycomb pattern.

12. The molding tool according to claim 1, wherein the pressing surface is rotationally symmetrical with respect to an axis of symmetry and the non-stick structure covers at least one region of the pressing surface which forms a normal angle of less than 20 with respect to the axis of symmetry of the pressing surface.

13. The molding tool according to claim 1, wherein there is an area extensively outside the non-stick texture on the pressing surface, the surface of which is essentially smooth relative to the non-stick texture.

14. The molding tool according to claim 13, wherein the pressing surface is dome-shaped and an area of the non-stick texture corresponds to a first inner concentric region of the pressing surface, wherein an outer smooth second region of the pressing surface is located around the non-stick texture and wherein the first region makes up 10% to 60% of the pressing surface and the second region makes up the rest of the pressing surface.

15. The molding tool according to claim 1, wherein the local recess structures have on average a closest distance of 0.01 mm to 0.04 mm to one another.

16. The -molding tool according to claim 1, wherein it consists essentially of high-speed steel.

17. The molding tool according to claim 1, wherein the recess structures each have a depth of 0.08 mm to 0.14 mm.

18. The molding tool according to claim 6, wherein the recess structures are laser engraved by a laser with a focus diameter of 0.02 mm to 0.1 mm.

19. The molding tool according to claim 9, wherein the local recess structures each have a maximum extensive expansion of 0.0003 mm.sup.2 to 0.008 mm.sup.2 at half their depth.

20. The molding tool according to claim 14, wherein the first region makes up 20% to 50% of the pressing surface.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0079] The drawings used to explain the exemplary embodiment show:

[0080] FIG. 1 a cross-section of a first molding tool according to the invention;

[0081] FIG. 2a an enlarged view of the pressing surface of the first molding tool;

[0082] FIG. 2b a direct view of the pressing surface of the first molding tool;

[0083] FIG. 3 a schematic representation of the structure of the non-stick texture;

[0084] FIG. 4 a schematic cross-section of a recess structure; and

[0085] FIG. 5a-f various other molding tools according to the invention as a direct view onto their respective pressing surface, wherein these have different structurings of the non-stick texture.

[0086] In principle, the same reference symbols are used for the same parts in the figures.

WAYS TO IMPLEMENT THE INVENTION

[0087] FIG. 1 to FIG. 4 schematically show a molding tool 1 according to the invention for use in pressing operations for pressing coffee powder and various partial areas of the molding tool 1.

[0088] FIG. 1 shows the molding tool 1 according to the invention as a cross-section in a plane containing an axis of symmetry 1z of the cylindrically symmetrical molding tool 1. The molding tool 1 essentially consists of a cylindrical body, the shaft 1s, which is approximately six times longer (horizontally in the image plane of FIG. 1) than it is wide (vertically in the image plane of FIG. 1). The molding tool 1 is solid and made of hardened high-speed steel of the grade HS6-5-2-5. For ease of presentation, the molding tool 1 is shown in a shortened form in FIG. 1, wherein the molding tool 1, or its shaft 1s, is cylindrical between the curved interruption lines with an unchanged constant diameter.

[0089] At one end of the shaft 1s, there is a mounting area 1b with a smaller diameter than the shaft 1s, which allows the molding tool 1 to interact with an axial drive component (not shown), for example. At the other end of the shaft 1s, there is a dome-shaped pressing surface 2, which is formed by an indentation at the shaft end. The pressing surface 2 is also (apart from the non-stick texture 3, see FIG. 3 and FIG. 4) symmetrical to the axis of symmetry 1z of the molding tool 1. Its lowest point, relative to the shaft 1s, is thus located on the axis of symmetry 1z and its depth decreases uniformly in all directions. The pressing surface 2 is designed to come into contact with the coffee powder to be pressed during pressing operations.

[0090] Two identically constructed molding tools 1 can, for example, interact with a stationary part whose inner geometry corresponds to a spherical layer in order to jointly produce spherical compacts.

[0091] The area of pressing surface 2 is shown enlarged in FIG. 2a in the same view as in FIG. 1. The pressing surface 2 extends over the entire width of the molding tool 1 and thus forms the entire end of the shaft 1s. The pressing surface 2 is completely concave with a variable curvature, wherein the radii of curvature are in the range of approximately 45% to 55% of the width of the molding tool. Thus, the pressing surface 2 forms an arched shape at the sectional plane, which extends over the entire width of the molding tool 1. The radius of curvature of the bulge of pressing surface 2 is about 20% greater at the edge than in the central area of pressing surface 2. The areas of pressing surface 2 that lie behind the sectional cutting plane are also shown schematically in FIG. 2a.

[0092] FIG. 2b shows the molding tool 1 as a direct view onto the pressing surface 2. The pressing surface 2 is divided into two subregions, the smooth region 2r in the edge region and the non-stick texture 3 in the central region of the pressing surface 2. Both regions are rotationally symmetric with respect to the axis of symmetry 1z of the molding tool 1 (FIG. 1). The non-stick texture 3 makes up about 35% of the total pressing surface 2 (this proportion appears larger when viewed directly from above), while the smooth region 2r makes up the remaining part of the total pressing surface 2. In the smooth region 2r, the pressing surface 2 corresponds to a polished metal surface of the material of the molded body (high-speed steel of the type HS6-5-2-5) without any further texture.

[0093] FIG. 3 schematically shows the structure of the non-stick texture 3 of the pressing surface 2 of the molding tool 1, wherein the molding tool 1, or the pressing surface 3, is shown in the upper left region analogous to FIG. 2b. In a first enlargement, indicated by two connected rings, the structuring of the non-stick texture 3 is illustrated. The non-stick texture 3 is formed by a multiplicity 4 of macro-areas. The macro-areas of the multiplicity 4 have the shape of regular hexagons (except at the round outer edge of the non-stick texture 3, where they are cut off) and are arranged in a hexagon honeycomb pattern. The macro-areas of the multiplicity 4 are uniform and of the same type, except for the edge area and the deformation caused by the curvature of the pressing surface. All macro-areas (except for the truncated areas at the edge) each have an area of approximately 1 mm.sup.2 and each consist of a subset (e.g. subset 5.1 in FIG. 3) of a multiplicity 5 of recess structures, each with adjacent raised structures. Between different macro-areas are regions on which there are no recess structures according to the invention. In these regions, the pressing surface 2 corresponds largely to the smooth region 2r outside the non-stick texture.

[0094] Another schematically drawn enlargement by two connected rectangles in FIG. 3 shows, for example, the composition of macro-area 4.1 (and thus of all macro-areas of multiplicity 4) by a subset 5.1 of multiplicity 5 of recess structures, each with adjacent raised structures. For example, the recess structure 5.1.1 is surrounded by the adjacent raised structure 5.1.1e (see FIG. 4 and description below). The recess structures of the subset 5.1 are arranged in a regular lattice-like manner within the macro-area 4.1 and cover the entire surface of the macro-area 4.1 on the pressing surface 2. All distances between two nearest neighboring recess structures within the multiplicity of 4 macro-areas, and thus also distance 5.1a within macro-area 4.1, are 0.02 mm. The distance 5.1a corresponds to the shortest distance along the pressing surface 3 from half the depth of a recess structure (in this case recess structure 5.1.1) to the next adjacent recess structure.

[0095] The multiplicity 5 of recess structures of the non-stick texture 3 is laser engraved. The recess structures are created in a laser engraving process in which the surface to be engraved is irradiated with laser pulses from an ytterbium fiber laser at a laser incidence angle of less than 20. The focus diameter of the ytterbium fiber laser used to laser engrave the recess structures is 0.05 mm and its depth of focus is approximately 1 mm. Each recess structure of multiplicity 5 is laser engraved with 30 individual ablations of 0.0004 mm each. The extensive expansion of each recess structure of multiplicity 5 is in the region of 0.0003 mm.sup.2 to 0.008 mm.sup.2. The raised structures have a height of 0.01 mm to 0.14 mm.

[0096] FIG. 4 shows an example of the recess structure 5.1.1 on the pressing surface 2 of the molding tool 1 as a schematic cross-section, wherein the sectional plane contains the local surface normal of the pressing surface 2 at the location of the lowest point of the recess structure 5.1.1. The recess structures of the multiplicity 5 are not exactly uniform and the remaining recess structures differ in detail from the shape shown.

[0097] The recess structure 5.1.1 is a depression on the pressing surface 2 that is rotationally symmetrical to the local surface normal of the pressing surface 2, with a depth 5.1.1t of 0.012 mm. The recess in the surface of the pressing surface is created through material removal by the applied laser pulses.

[0098] The recess structure 5.1.1 has a maximum extensive expansion of 0.002 mm.sup.2 at half its depth 5.1.1t and a diameter of 0.05 mm at its half depth 5.1.1t.

[0099] The upper edge of the recess structure 5.1.1 also forms the upper edge of a raised structure 5.1.1e, which surrounds the recess structure 5.1.1 in a ring shape. The raised structure 5.1.1e has a height 5.1h of 0.003 mm. The raised structure 5.1.1e is formed by a partial deposition of the material removed during the laser engraving of the recess structure 5.1.1.

[0100] The non-stick texture 3 of the molding tool 1 of such a condition effectively prevents coffee powders of different types from adhering to the pressing surface 2 of the molding tool 1, even during pressing operations involving comparatively high pressures.

[0101] FIG. 5a to FIG. 5f show various alternative embodiments of the inventive molding tool 100, . . . , 600 for pressing coffee powder, which differ in the structuring of the respective non-stick texture 103, . . . , 603. FIG. 5a to FIG. 5f show the respective molding tool 100, . . . , 600 in a direct view onto its pressing surface 102, . . . , 602, analogous to FIG. 2b. The nature of the molding tools 100, . . . , 600 from FIG. 5a to FIG. 5f corresponds to the nature (except for the respective non-stick texture 103, . . . , 603) of the molding tool 1 from FIG. 1 to FIG. 4. The non-stick textures 103, . . . , 603 of the designs in FIG. 5a to FIG. 5f correspond in their extent to the non-stick texture 3 of the molding tool 1 from FIG. 1 to FIG. 4 and consist of a multiplicity of recess structures, which (except for the number of recess structures) correspond to the multiplicity 5 of recess structures of the molding tool 1. The black areas of the respective non-stick texture 103, . . . , 603 shown in FIG. 5a to FIG. 5f correspond to macro-areas composed of recess structures, within which the respective closest distances between two recess structures are 0.02 mm. The white regions of the non-stick textures 103, . . . , 603 correspond to regions of the respective pressing surface 102, . . . , 602, within which there are no inventive recess structures. The non-stick textures 103, . . . , 603 also effectively prevent coffee powder from adhering during pressing operations.

[0102] FIG. 5a shows a molding tool 100 with a pressing surface 102 on which a non-stick texture 103 is located. The multiplicity of recess structures of the non-stick texture 103 is distributed on the pressing surface 102 in such a way that the non-stick texture imitates the appearance of a (finely structured) leather surface.

[0103] FIG. 5b shows a molding tool 200 with a pressing surface 202 on which a non-stick texture 203 is located. Here, the multiplicity of recess structures of the non-stick texture 203 is distributed over the pressing surface 202 in such a way that the non-stick texture 203 imitates the appearance of a (finely structured) fabric surface, e.g. linen.

[0104] FIG. 5c shows a molding tool 300 with a pressing surface 302 on which a non-stick texture 303 is located. The multiplicity of recess structures of the non-stick texture 303 is distributed on the pressing surface 302 in such a way that the non-stick texture reproduces a wave pattern on the pressing surface 302. The wave-shaped macro-areas have an area of 0.1 to 2 mm.sup.2.

[0105] FIG. 5d shows a molding tool 400 with a pressing surface 402 on which a non-stick texture 403 is located. The multiplicity of recess structures of the non-stick texture 403 is distributed on the pressing surface 402 in a dot pattern in which larger dots (with an area of approximately 10 mm2) are located near the center of the pressing surface 402 and the diameter of the dots decreases towards the edge of the non-stick texture 403.

[0106] FIG. 5e shows a molding tool 500 with a pressing surface 502 on which a non-stick texture 503 is located. The multiplicity of recess structures of the non-stick texture 503 is arranged in parallel lines that are evenly spaced apart and that run completely through the non-stick texture 503. In terms of width, each line (of approx. 0.1 mm) also encompasses several recess structures located next to one another. The distance between the individual lines is 0.5 mm.

[0107] FIG. 5f shows a molding tool 600 with a pressing surface 602 on which a non-stick texture 603 is located. The multiplicity of recess structures of the non-stick texture 603 is arranged in regularly spaced grid lines, which form a regular and uniform grid pattern. Two parallel adjacent grid lines are approximately 1 mm apart. Within each grid line, there are also several adjacent recess structures across the width of the grid line (approx. 0.1 mm).

[0108] The invention is not limited to the exemplary embodiments set forth above. For example, the molding tool may have a different shape, for example with a longer or shorter shaft, or a shaft with further regions in which its diameter varies. Also, the molding tool may have a more complex geometry, for example for cases in which it is not intended to move the molding tool and it interacts, for example, with a moving pressing tappet. In addition, the molding tool can be made of a different material, such as 304L stainless steel. Furthermore, the pressing surface can be made of a different material than the rest of the molding tool, for example, by means of a coating.

[0109] The pressing surface need not be rotationally symmetrical, but can have an oval or square profile. The pressing surface can also have a more complex shape that presses designs or lettering into a molded body. The molding tool as a whole does not necessarily have to be rotationally symmetrical either. The extent of the non-stick texture may be smaller or larger than in the exemplary embodiments shown and its edge may have a shape other than a round one. For example, the non-stick texture may also be rectangular or star-shaped. The recess structures may also not be laser engraved, but may be pressed in, for example, or laser engraved with a different type of laser. The recess structures can also be laser engraved with more or fewer individual ablations. The closest distance between the recess structures can be greater or smaller. The recess structures can also have a depth other than 0.012 mm or have a different maximum dimension. Furthermore, the non-stick texture, especially in the case of non laser engraved recess structures, may also have no elevations or elevations that are not arranged around the recess structures. Furthermore, the shown shape of the recess structure is purely exemplary and may differ from the example (even within a molded body).

[0110] The structuring of the non-stick texture shown, e.g. as hexagonal macro-areas, is just one possible design. There are countless other patterns or structures that could be used, for example, uniformly dotted patterns, uniform filling of the entire non-stick texture with recess structures, a random arrangement of the recess structures (e.g. according to a Monte Carlo method), tiling with square or rectangular macro-areas, a wood look imitation and many more. The molding tool can also be designed for other powder materials than coffee powder or can be used in the form shown for other powder materials than coffee powder.

[0111] In summary, it can be stated that an extensive non-stick texture with a multiplicity of local recess structures, wherein the recess structures each have a depth of 0.04 mm to 0.2 mm, in particular a depth of 0.08 mm to 0.14 mm, creates a molding tool that effectively prevents powder material from adhering during pressing operations.